You will need at least 4 people. Play "Adam Grab" and wait until the match ends. Do NOT pick up the sister.When the game ends with everyone on 0 points, the game will count it as a win for everyone.

You can still work on XP by hacking turrets or you can work on challenges. Every match takes 10 minutes.You will notice after the 6 matches that you got the achievement for playing on each DLC map but not for winning. Only the host of the last map will get it at this point. The player who is going next for the achievement has to pick up the little sister for 3 minutes in the next match. As soon as the match ends the achievement will pop for him too. Repeat this until everybody is done.

Make sure everybody got the DLC or you will not be able to play on these maps.